Answer:
They will have the same amount of money in their piggy banks when they each reach $6. (4 days for Joseph, 3 for Kelsey.)
Step-by-step explanation:
Joseph has $3.00 and will add $0.75 cents to it each day. So for the first day he will have $3.75. Then, $4.50. Then, $5.25. Then on the fourth day, he will have $6.
Kelsey has $5.25 and will add $0.25 each day. For the first day, she will have $5.50 in her piggy bank. Then, $5.75. Then $6.